Quick shut-off device for grinding tool

ABSTRACT

A grinding tool includes a handle with a grinding wheel connected thereto and driven by a driving device. An opening is defined in the handle and a switch device is received in the opening with which a cover is engaged. A recess is defined in an outer periphery of the cover and a hole is defined through the cover. A pushing member is slidably engaged with the recess and a stepped protrusion extending from an underside of a first end of the pushing member is engaged with an inner periphery of the hole. A gap is defined between a second end of the pushing member and a surface defining the recess. An activation member is connected to the sliding member via the hole and has a convex contacting the switch device. A spring is connected between the cover and the activation member. The activation member shuts off the switch device when the sliding member is pulled by the spring by pushing the second end of the pushing member.

FIELD OF THE INVENTION

[0001] The present invention relates to a quick shut-off device for agrinding tool and includes a pushing member connected to a spring sothat when the user pushes an end of the pushing member, the switch ofthe grinding tool is then shut off immediately.

BACKGROUND OF THE INVENTION

[0002] A conventional portable grinding tool is shown in FIG. 1 andgenerally includes a handle 70 with a driving device 72 connected to afirst end of the handle 70 and a grinding wheel 71 is connected to anddriven by the driving device 72. A switch 73 is connected to a secondend of the handle 70 so that the driving device 72 is activated orstopped by operating the switch 73. The grinding tool is heavy so thatthe user usually holds the handle 70 with his/her two hands. In asituation when the grinding wheel 71 is broken by an impact with a hardobject, the debris could fly to hit the user at a high speed and theuser has to shut off the driving device 72 as soon as possible. However,when the grinding tool is operated in a narrow space, the two hands ofthe user are not convenient to remove from the handle 70 to operate theswitch 73. Therefore, how to shut off the driving device 72 within ashort period of time when the emergency situation happens is important.

[0003] Referring to FIG. 2 which shows another type of the conventionalgrinding tool 80 and the switch 81 is connected to a surface of thehandle 82 and the switch 81 extends from the surface of the handle 82.The switch 81 is easily to be touched or activated when putting the tool80 on the ground, or by unintentional access. This will activate thegrinding wheel 83 without expectation and could hurt the grinding wheel83 and/or the people around the grinding tool 80.

[0004] The present invention intends to provide a quick shut-off devicefor the grinding tool that has a pushing member on the handle and can betouched to shut off the electric power to stop the driving device.

SUMMARY OF THE INVENTION

[0005] In accordance with one aspect of the present invention, there isprovided a grinding tool which comprises a handle having a drivingdevice at a first end of the handle so as to drive a grinding wheel. Anopening is defined in the handle and a switch device is received in theopening. A cover is engaged with the opening and has a recess defined inan outer periphery of the cover. A hole is defined through the cover.

[0006] A pushing member is slidably engaged with the recess and astepped protrusion extends from an underside of a first end of thepushing member so as to be engaged with an inner periphery of the hole.A gap is defined between a second end of the pushing member and asurface defining the recess.

[0007] An activation member extends through the hole and is locatedbetween the stepped protrusion and the second end of the pushing member.The activation member is fixed to the pushing member and has a convexwhich contacts the switch device.

[0008] A spring has a first end connected to the cover and a second endof the spring is connected to the activation member.

[0009] The present invention will become more obvious from the followingdescription when taken in connection with the accompanying drawingswhich show, for purposes of illustration only, a preferred embodiment inaccordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a perspective view to show a conventional grinding tool;

[0011]FIG. 2 is a perspective view to show another embodiment of theconventional grinding tool;

[0012]FIG. 3 is a perspective view to show the grinding tool of thepresent invention;

[0013]FIG. 4 is an exploded view to show the quick shut-off device ofthe grinding tool of the present invention;

[0014]FIGS. 5A, 5B and 5C show the steps of setting the pushing memberto start the switch device of the grinding tool of the presentinvention;

[0015]FIG. 6 is a cross sectional view to show the pushing member ispushed to shut off the switch device, and

[0016]FIGS. 7A, 7B and 7C show the steps of releasing the pushing memberto shut off the switch device of the grinding tool of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017] Referring to FIGS. 3, 4, and 5A, the grinding tool of the presentinvention comprises a handle 50 having a driving device 51 connected toa first end of the handle 50 and a grinding wheel 60 is connected to anddriven by the driving device 51. An electric cable is connected to asecond end of the handle 50. An opening is defined in the handle 50 anda seesaw type switch device 10 is received in the opening. A cover 20 isengaged with the opening and has a recess 21 defined in an outerperiphery of the cover 20 and a hole 22 is defined through the cover 20.

[0018] A pushing member 40 is slidably engaged with the recess 21 and astepped protrusion 42 extends from an underside of a first end of thepushing member 40 so as to be engaged with an inner periphery of thehole 22. A gap is defined between a second end of the pushing member 40and a surface defining the recess 21. A pushing ridge 43 extends from atop surface of the pushing member 40 so that the user may push thepushing member 40 by using a thumb to push the pushing ridge 43.

[0019] An activation member 30 extends through the hole 22 of thepushing member 40 and is located between the stepped protrusion 42 andthe second end of the pushing member 40. The activation member 30 has aconvex 33 which contacts the switch device 10 and a hole 32 is definedthrough the convex 33 so that a screw 35 extends through the hole 32 andis threadedly engaged with a threaded hole 41 defined in an underside ofthe pushing member 40.

[0020] A spring 24 has a first end connected to the cover 20 and asecond end of the spring 24 connected to an extension portion 300 of theactivation member 30 as shown in FIG. 5A.

[0021] As shown in FIGS. 5B and 5C, the pushing member 40 is pushed toextend the spring 24 by pushing the pushing ridge 43 till the steppedprotrusion 42 on the underside of the first end of the pushing member 40is engaged with the inner periphery of the hole 22. At this position,the seesaw switch device 10 is set at start position and the grindingtool is in operation condition.

[0022] Referring to FIGS. 6, 6A, 6B and 6C, when in emergency situationand the grinding tool has to be shut off immediately, the user may pushthe second end of the pushing member 40 and the first end of the pushingmember 40 is then raised to disengage the stepped protrusion 42 from theinner periphery of the hole 22, the pushing member 40 is then pulled bythe spring 24 and the convex 33 pushes the switch device 10 to stopposition. It is to be noted that the user simply pushes the second endof the pushing member 40, the spring 24 pulls the pushing member 40 andthe switch device 10 immediately shut off.

[0023] While we have shown and described the embodiment in accordancewith the present invention, it should be clear to those skilled in theart that further embodiments may be made without departing from thescope of the present invention.

What is claimed is:
 1. A grinding tool comprising: a handle having adriving device connected to a first end of the handle and a grindingwheel connected to and driven by the driving device, an electric cableconnected to a second end of the handle, an opening defined in thehandle and a switch device received in the opening; a cover engaged withthe opening and having a recess defined in an outer periphery of thecover, a hole defined through the cover; a pushing member slidablyengaged with the recess and a stepped protrusion extending from anunderside of a first end of the pushing member so as to be engaged withan inner periphery of the hole, a gap, defined between a second end ofthe pushing member and a surface defining the recess; an activationmember extending through the hole and located between the steppedprotrusion and the second end of the pushing member, the activationmember fixed to the pushing member and has a convex which contacts theswitch device, and a spring having a first end connected to the coverand a second end of the spring connected to a combination of theactivation member and the cover.
 2. The grinding tool as claimed inclaim 1, wherein the activation member has an extension portion to whichthe second end of the spring is connected.
 3. The grinding tool asclaimed in claim 1, wherein the activation member has a hole definedthrough the convex and a screw extends through the hole and isthreadedly engaged with the pushing member.
 4. The grinding tool asclaimed in claim 1 wherein the sliding member has a pushing ridgeextending from a top surface thereof.